The Law of Attraction: Relating Computed Energetics of Physisorption with Performance of Graphene-Based Sensors for Nitroaromatic Contaminants

The ability to detect persistent nitroaromatic contaminants, e.g. DNT and TNT, with high sensitivity and selectivity is central to environmental science and medicinal diagnostics. Graphene-based materials rise to this challenge, offering supreme performance, biocompatibility, and low toxicity at a reasonable cost. In the first step of the electrochemical sensing process, these substrates establish non-covalent interactions with the analytes, which we show to be indicative of their respective detection limits. Employing a combination of semiempirical tight binding quantum chemistry, meta- dynamics, density functional theory, and symmetry-adapted perturbation theory in conjunction with curated data from experimental literature, we investigate the physisorption of DNT and TNT on a series of functionalised graphene derivatives. In agreement with experimental observations, systems with greater planarity and positively charged substrates afford stronger non-covalent interactions than their highly oxidised distorted counterparts. Despite the highly polar nature of the investigated species, their non-covalent interactions are largely driven by dispersion forces. To harness these design principles, we considered a series of boron and nitrogen (co)doped two-dimensional materials. One of these systems featuring a chain of B–N–C units was found to adsorb nitroaromatic molecules stronger than the pristine graphene itself. These findings form the basis for the design principles of sensing materials and illustrate the utility of relatively low cost in silico procedures for testing the viability of designed graphene-based sensors for a plethora of analytes.